A medium-sized, all-dark stork with a mostly greenish gloss and a uniquely-shaped bill that creates a diagnostic gap between the two halves of the bill. Its flight is slow and laboured. The long neck and feet separate it from other dark waterbirds. It prefers still waters in shallow lakes, swamps and seasonal pans, where it uses its odd bill to extract snails and mussels from their shells. A resident, migrant and nomad; massive numbers can suddenly appear when conditions are favourable.